34 



BULLETIN 257, IT. S. DEPARTMENT OE AGRICULTURE. 



Table 25. — Surface maintenance of 1911 experiments at Chevy Chase, Md., to December 



31, 1914. 



Experi- 

 ment No. 



Date 

 com- 

 pleted. 



Area 

 (square 

 yards). 



Maintenance cost of experiment. 



Cost per square yard (cents). 



1912 



1913 



1914 



Total. 



Construc- 

 tion. 



Mainte- 

 nance. 



Total. 



1 



1911. 

 Oct. 31 

 ...do 



1,581 



705 



1,555 



1,555 



1,447 



1,555 



131 



848 



1,477 

 761 



1,013 

 377 



SO. 00 



.00 



.00 



.00 



260. 26 



.00 



1.43 



67.88 



SO. 00 



.00 



.00 



4.05 



2.31 



3.47 



.00 



.00 



80.64 



39.65 



19.05 



.00 



S91. 33 

 .00 

 .00 



1.90 

 .67 

 .00 

 .00 



1.33 



.00 



44.78 



284. 04 



.00 



S91. 33 



.00 



.00 



5.95 



263. 24 



3.47 



1.43 



69.21 



80.64 



84.43 



303. 09 



.00 



46.18 

 77.62 

 64.69 

 57.16 

 58.27 

 68.22 

 59.96 

 54.80 



39.59 



42.01 

 44.31 

 81.51 



5.777 



.000 



.000 



.383 



18. 192 



.223 



1.092 



8.162 



5.460 



11.095 



29. 920 



.000 



51.96 



2 



77.62 



3 



d 



Nov. 18 

 Nov. 8 

 Dec. 2 

 Nov. 23 

 Dec. 5 

 ...do 



1912. 

 Aug. 24 

 June 4 

 Nov. 22 

 Dec. 16 



64.69 

 57.54 



5... 



76.46 



6 



68.44 



7A 



7B 



8 



61.05 

 62.96 



45.05 



9. . 





53.11 



10 . 





74.23 



11.. 





81.51 









SUPPLEMENTARY REPORT OF EXPERIMENTS MADE AT JAMAICA, N. Y., 



1911. 



OIL-CEMENT CONCRETE, OIL-ASPHALT, TAR, AND FLUXED NATIVE ASPHALT. 



The original report of these experiments was published in Circular 

 No. 98, and reports of annual inspection and repairs may be found 

 in Circular No. 99, Office of Public Roads, and in U. S. Depart- 

 ment of Agriculture Bulletin No. 105. The following report covers 

 the condition of the sections when inspected January 18, 1915. 



Experiment No. 1 (Oil-Cement Concrete). 



In May, 1914, the Borough of Queens highway department patched 

 the bare spots which were reported in the inspection of December, 

 1913, with an application of hot, refined coal tar and sand, and the 

 addition of f-inch stone in the deeper holes. The bare spots had 

 developed somewhat larger in the section treated with water-gas tar 

 products than in that treated with refined coal tar. At the time of 

 the inspection the entire section was in very good condition with the 

 exception of about 20 small bare spots where the carpet coat had 

 worn off. The entire coat seemed to be worn very thin. 



Experiment No. 2 (Cut-Back Oil Asphalt — Mixing Method). 



In May, 1914, the condition of this experiment was a little worse 

 than in December, 1913, and in consequence the entire section was 

 scarified to a depth of 3 inches and about one-third of the soft 

 bituminous top mixture was thrown away. The remaining mixture 

 was then shaped and lightly rolled to a thickness of about 2 inches, 

 after which it was covered with a thin layer of f-inch stone, thoroughly 

 rolled, and opened to traffic. The following day a thin layer of 

 trap-rock screenings was rolled in. 



